This invention relates to further improved orthodontic screw-type biassing devices, and more particularly to an improvement for preventing backing off of the screw which imparts biassing forces.
The object of the present invention is to provide an orthodontic biassing device, of the type which utilizes a screw for applying biassing forces, which substantially prevents or substantially reduces the screw back-off inherent in existing prior art devices.
It is a further object of the invention to provide an orthodontic biassing device, of the type which utilizes a screw for applying biassing forces, which has sufficient looseness and play to enable easy installation in the mouth, but which when after installation and under expansion conditions, provides a substantially rigid structure, as required.